Process of making high strength,high density,highly ductile uranium-titanium alloy

ABSTRACT

The step of furnace tempering a solution treated, waterquenched, worked cast ingot at 600*F for about 4 hours in an inert atmosphere and permitting the ingot to furnace cool in that atmosphere yields an uranium-1.25 titanium alloy having the following physical properties: Tensile strength : 234,700 psi Yield strength : 172,700 psi Elongation in 1 inch : 17% Nominal density : 18.

2:1: atent [191 Edelm et a represented by the Secretary of the Army,Washington, DC.

[22] Filed: Oct. 1, 1971 [21] Appl. No.: 185,812

[52] US. Cl. 148/ll.5 F, 102/52, 148/132 [51] Int. Cl C2ld 1/18, F42b11/14 [58] Field of Search 148/132, 11.5 R,

[56] References Cited OTHER PUBLICATIONS Douglass et aL, Effect of HeatTreatment on the Hard- Nov. 20, 1973 ness and Microstructure of U-TiAlloys, in J. Met. 9:1. 1260-1267, Oct. 1957.

Primary Examiner--Carl D. Quarforth Assistant Examiner-R. E. SchaferAttorney-Harry M. Saragovitz et al.

[57 ABSTRACT The step of furnace tempering a solution treated,water-quenched, worked cast ingot at 600F for about 4 hours in an inertatmosphere and permitting the ingot to furnace cool in that atmosphereyields an uranium- 1.25 titanium alloy having the following physicalproperties:

Tensile strength 234,700 psi Yield strength 172,700 psi Elongation in 1inch 17% Nominal density 18.5g/cc 6 Claims, No Drawings PROCESS OFMAKING HIGH STRENGTH, HIGH DENSITY, HIGHLY DUCTILE URANIUM-TITANIUMALLOY The invention described herein may be manufacduction furnace atroom temperature, the furnace temperature then being brought to about2,800F and held at this temperature until the melt is substantiallyhomogeneous.

tured, used, and licensed by or for the Government for 5 Thc titaniumwill preferably comprise L25 we'ght governmental purposes without thepayment to us of percent 9 the alloy but may range m {about to anyroyalty thereon 1.40 weight percent thereof. lf quantities less thanThis invention relates to alloys and more particularly about we'ghtpercent f g i we gi concerns processes for fabricating a high strength,high I 0 found C ac li g f or density, highly ductile uranium-titaniumalloy. armor'plercmg onverse w en t e mamum exceeds about 1.40 weightpercent of the alloy, an un- Armor-piercing pro ectiles and the like formodern desirably brittle piece results. day munitions must be strong,ductile, and of high den- Sit The melt may now be poured into anothermold, suitzy t td th ably magnesia, alundum, thoria, and the like, toform I i uc l I e armortplercmg ,pene' a rod or bar shaped casting ofdesired dimensions. This "atolmlght fragment or fracture. upon with ancast ingot will now be worked, by extrusion, forging, enemy target thetarget compnses but Smgle armor rolling, etc. and then subjected to aheat treatment as layer, fragmenting of the penetrator upon impacttherefollows, with might not be unduly detrimental. Where, however,solution treat the worked cast ingot at 0 0 enemy targets compnse spcedarmof F x m for about 16 hours. The ingot may be placed in the vacmanymodem tanks a flymg craft It lmiferatwe uum furnace while maintained atroom temperature or that the armor-piercing penetrator remain integralat the desired end temperature of o 7 o upon impact if successfulpenetration of the layers is to The Solution treated ingot will the beremoved from be acheved' the vacuum furnace and immediately waterquenched i' i the armor'plercfng molecules must be prior to a temperingtreatment which comprises placing sufficiently strong to withstandimpact and be of suffithe quenched ingot alloy in a furnace maintainedat ciently high density to render them capable ofpenetratroomtemperature comaining an inert atmosphere, ing these enemy targets. Inthls regard, prior art armorpreferably heliunL The furnace is brought upto 0 P g penetratorS and proiectlles do not P0556SS in about 1 hour,held for 4 more hours, and permitted high strength, high density andhigh ductility properties to cool to about room temperature in abouthours, Yequll'ed of modem y munmonsthe inert atmosphere being maintainedthroughout. It it is therefore an object Of thlS invention to provide isthis tempering o ageing step is considered an alloy having highStrength. g density, and hlgh vital in the retention of desiredductility and strength. ductility- More specifically, our melt was castinto ingots hav- Another object of the invention is to provide such an ia di f 2 d a l th f b t 3 i h alloy which would make it ideally suitablefor armOr- Th were forged in air at approximately 1650F into piercingcapabilities. 3 1 inch diameter rods, then hot swaged at approxi- Theexact nature of this invention as well as other obmately 1650F t ya i hdiam t They w then majects and advantag s there f ll be e i y app chinedto remove the forged surfaces prior to the heat from consideration ofthe specification that follows. 40 treatment above described.

ln accordance with the above objects, we have dis- Tensile bars were cutfrom these heat treated bars. covered that a uranium base alloy whichincludes a The table below lists various mechanical properties of minorproportion of titanium, will yield a highly ductile these specimens forour preferred alloy composition.

TABLE I High strength, high ductility, high density U-TI alloy TensileYield Nominal strength, strength, Elongation in density, Number AlloyHeat treatment p.s.i. p.s.i. 1 g./cc.

i 98.75U1.25Ti. 1,650l.700 F.16 hours in vacuo; water quenched; 600 F.-4hours 234, 700 172, 700 17% 18.5

(helium); furnace cooled in helium. .2 98.75U1.25Ii Same as No. 1,except specimen air cooled instead of furnace cooled 200,000 176,0007.2% 18. 5 154,000 l'oke bn'ttely.- 18.5

3 98.76U1.25Ti. Same as No. 2, except Water quenched alloy having goodstrength and density when said alloy is made in accordance with ourprocess steps.

More specifically, we have found that when about 1.25 weight percenttitanium is alloyed with the uranium, an alloy can be formed when usingour inventive process steps having a tensile strength of 234,700 psi; ayield strength of l72,700 psi; an elongation in 1 inch of 17 percent;and a nominal density of about 18.5g/cc.

ln producing our inventive alloy, we place a measured quantity ofcommercial, high purity (99.9 percent) uranium dingot at the bottom of acrucible, suitably of magnesia or graphite+ceramic-wash, and titaniumsponge of commercial purity thereabove, the crucible and contents thenbeing placed in a vacuum in- We wish it to be understood that we do notdesire to I be limited to the exact details described, for obvioustempering said quenched ingot alloy at 600F for a period of about 4hours in an inert atmosphere,

furnace cooling said tempered ingot alloy in said inert atmosphere. and

shaping said cooled tempered ingot alloy into said armor-piercmgmunition.

2. The process as described in claim 1 wherein said titanium is presentin said alloy in an amount of 1.25 weight percent, the balance beingsubstantially uranium, and wherein tensile strength of said alloy isabout 234,700 psi, yield strength of said alloy is about 172,700 psi,elongation in 1 inch of said alloy is about 17 percent and nominaldensity of said alloy is about 18.5g/cc.

3. The process as described in claim 2 wherein said worked ingotcomprises the steps of forging said ingot in air at about 1,650F, andhot swaging said forged ingot prior to said solution treatment. 4. Theprocess as described in claim 2 further characterized by said inertatmosphere being helium.

5. The process as described in claim 2 further characterized by saidtempering step comprising placing said water quenched ingot in a furnacemaintained at room temperature in said inert atmosphere, raising thetemperature of said furnace to about 600F in a period of about 1 hourwhile maintaining said inert atmosphere. 6. The process as described inclaim 5 further characterized by said inert atmosphere being helium.

2. The process as described in claim 1 wherein said titanium is presentin said alloy in an amount of 1.25 weight percent, the balance beingsubstantially uranium, and wherein tensile strength of said alloy isabout 234,700 psi, yield strength of said alloy is about 172,700 psi,elongation in 1 inch of said alloy is about 17 percent and nominaldensity of said alloy is about 18.5g/cc.
 3. The process as described inclaim 2 wherein said worked ingot comprises the steps of forging saidingot in air at about 1,650*F, and hot swaging said forged ingot priorto said solution treatment.
 4. The process as described in claim 2further characterized by said inert atmosphere being helium.
 5. Theprocess as described in claim 2 further characterized by said temperingstep comprising placing said water quenched ingot in a furnacemaintained at room temperature in said inert atmosphere, raising thetemperature of said furnace to about 600*F in a period of about 1 hourwhile maintaining said inert atmosphere.
 6. The process as described inclaim 5 further characterized by said inert atmosphere being helium.